Non-linear relationship between baseline mean arterial pressure and 30-day mortality in patients with sepsis: a retrospective cohort study based on the MIMIC-III database.

Background: Sepsis is a life-threatening organ dysfunction due to disturbance of the host's response to infection, and is often accompanied by shock. Timely and standardized hemodynamic management can effectively control disease progression. Mean arterial pressure (MAP) refers to tissue and organ perfusion and is one of the key factors for patient recovery. In this study, we focused on the relationship between MAP levels and 30-day mortality in patients with sepsis. Methods: This cohort study included 14,607 sepsis patients out of 38,597 adults admitted to Beth Israel Deaconess Medical Center in Boston between 2001 and 2012, according to the Sepsis 3.0 diagnostic criteria. According to the MAP value of the sepsis patients on the first day of intensive care unit (ICU) admission, they were divided into 5 groups (Q1 ≤67.4 mmHg, Q2 67.4-72.5 mmHg, Q3 72.5-77.6 mmHg, Q4 77.6-84.6 mmHg, Q5 ≥84.6 mmHg). At the same time, the baseline data of vital signs, critical illness score, comorbidities and laboratory examination were collected on the first day of admission to ICU. The 30-day mortality of the 5 groups of patients and the overall sepsis patients were recorded. Multivariate Cox regression analysis and smooth curve fitting were used to assess the independent association between MAP and 30-day mortality. Results: A total of 14,607 sepsis patients were screened. The mean age of participants was 67.2±16.3 years, approximately 46.9% were women, and the overall 30-day mortality rate was 21.0%. Multivariate Cox regression models and smooth curve fitting revealed a non-linear association between MAP and 30-day mortality. The inflection point occurred at 68.6 mmHg. The left side effect size of each 10-unit change in the exposure factor was [hazard ratio (HR): 0.479, 95% confidence interval (CI): 0.403-0.569, P<0.001]. To the right of the inflection point, the effect size was (HR: 0.996, 95% CI: 0.931-1.065, P<0.9018). Conclusions: Our study demonstrated a non-linear relationship between MAP and 30-day mortality in patients with sepsis. When MAP was less than 68.6 mmHg, it was a strong predictor of the potential risk of sepsis death, which declined by 52.1% for every 10 mmHg growth in MAP.